Following a deadly Boeing 737 crash last month in Indonesia, federal regulators and the aircraft manufacturer are warning pilots about the risk of inaccurate inputs from the flight monitoring system, which is designed to balance the plane.

The Federal Aviation Administration (FAA) released an Emergency Air Worthiness Directive on November 7, advising all pilots operating Boeing Model 737 Max jets that the Angle of Attack (AOA) sensors may produce erroneous readings and cause the plane to abruptly dive, increasing the risk of a crash.

According to the FAA, the planes are equipped with an AOA which measures the angular difference between the direction the aircraft is moving and the pitch of the aircraft’s wing. Boeing has discovered the system can produce inaccurate measurements telling pilots the nose of the plane is too high in relation to the current of air. As a result, pilots may continue to pitch the nose downward or the automatic system may forcibly pitch the nose down.

The Emergency Directive was issued for the new Boeing 737-8 and -9 MAX airplane models after an investigation following a fatal Lion Air crash involving one of the new planes. To date, it has not been determined whether the AOA malfunction was related to the fatal crash, which killed all passengers and crew members onboard.

Lion Air Flight 610, a Boeing 737 Max, departed Jakarta, Indonesia airport on October 29, with 189 passengers and crew. The plane was destined for Pangkal Pinang, but crashed into the Java Sea approximately 20 minutes into the flight around 6:30 a.m., killing all on board.

Boeing issued a statement on October 29, expressing how deeply saddened the company was by the loss of Lion Air Flight JT 610 and extended their heartfelt sympathies to the families and loved ones on board.

The Boeing Company designs, manufactures and sells airplanes, rockets, satellites, and missiles worldwide based in Chicago, Illinois has been working with FAA officials to determine the reasoning for the crash.

The investigation has since discovered the possibility of the erroneous AOA readings, however it is unsure if these readings were the cause of the Lion Air Flight JT 610. Boeing has announced it will continue to seek the cause of the crash and will be providing further technical assistance under the direction of government authorities investigating the accident.